This research is directed to the experimental demonstration of recently predicted effects of electrical fields on phase changes and chemical composition in two-dimensional systems, and to extending the related thermodynamic theory from monolayers to bilayers and (by projection) to biomembranes. The outcome of these experiments and developments in theory will be to provide a phenomenological base for the description of field-dependent processes in biomembranes. The goals set for the current year were to build and commission a sensitive surface balance and related surface potential apparatus; and to take the thermodynamic theory a stage further towards bilayer and biomembrane systems.